Outdoor units for air-conditioning apparatuses in known arts each include devices, such as a heat exchanger, a fan, and a compressor, and a box-shaped casing that houses the devices. The outdoor unit allows a refrigerant to circulate between an indoor unit and the outdoor unit that are connected to each other by pipes. Heat is transferred to or received from air flowing through the heat exchanger, whereby a room is cooled or heated. Proposed examples of such a known outdoor unit for an air-conditioning apparatus include an outdoor unit that is intended to improve the performance of the air-conditioning apparatus by increasing the efficiency of heat transfer or heat reception. Such an outdoor unit includes a heat exchanger that has an L shape extending along two faces of a box-shaped casing so that the two faces of the casing are utilized, or a U shape extending along three faces of the casing so that the three faces of the casing are utilized while the position of a compressor is carefully considered (see Patent Literature 1, for example).